Water Level Sensor Selection

I've always had reliable success with non-contact ultrasonic switches. In some, we have also installed a float switch as a secondary "dead-man" option. You don't mention what fluid you're controlling the level of.

GA. I have used Ultrasonic for a variety of reasons. Some water reservoirs would require a different setting winter and summer for example. Ultra sonic lend itself to remote sensing and SCADA operation. They are also provide a very wide range of off/on with infinite adjustment. Non contact with the fluid so they were usually not prone to limiting conditions like hard water and sensor cleaning. Easy to install and relatively cost effective as a capital investment. Ultrasonic is very good if low maintenance is required.

Your engineer would know.

Roboto shave experience...

It also depends on contamination concerns, fail safe, MTBF, cycle time, accuracy and precision.

You can only know if you accomplished the job if somebody defines the job.

A perfect example of KISS engineering.

thats as basic as it gets

It all depends on the type of liquid,the environment surrounding the liquid and sensors.

I have seen applications for all types,each with their own attributes that made them the best fit.

Ultrasonics do not work well on liquids with heavily entrained air,the air absorbs the signal.

Steam heated tanks also generate ultrasound when steam is flowing,that can swamp

the sensor signal of an ultrasonic probe.

I have seen cases where the liquid was so corrosive that electrode types would not

survive for very long...(believe it or not this was 160 degree F water).

The turbulence in the liquid can create noise that is very hard to filter out,and a

stilling well is sometimes required.

So in other words,consult a instrumentation engineer and have all pertinent

information available for your particular application.

In regard to my shave experience, it extends over 55 years, it is generally irritating.

Rule #1: Wherever possible go contactless.

Rule #2: When you can't go contactless, use a system without moving mechanical parts (beside maybe some output relays on the PCB and a couple of programming keys).

Ultrasonic is a good candidate. The comment about interferences is only partially valid, good ultrasonic level measurement devices feature digital signal processing so it's not much a problem as long as the power of the transducer is sufficient. In case of doubt, make a test.

Using ultrasound level measurement one must pay attention to the blind zone (minimal distance) between the sensor and the liquid surface as even if you can flood many sensors they stop measuring correctly once the level has reached that distance.

Some compact foams can be a problem as well as fast stirring devices (slow ones are discriminated by the firmware) but overall ultrasound is often a good starting point.

Redundant analogic (mostly 4-20 mA) ultrasound or, if money is tight, 1x ultrasound + Non-mechanical level limit switch(es) are a good basic solution for non-critical applications.

Piezostatic measures work well in some cases (especially with water/wastewater), I mean with pressure cells, not pressure balance with compressed air, that belongs mostly to the past though it's still widely in use).

Electrodes are not good if there's a risk of deposit (especially also wastewater which can cause odd fat deposits) and must not end heavily corroded.

Floating switches are just a major PITA and will fail sooner or later. Use them at your own risk.

More expensive contactless level measurement devices like for example laser or radar are sometimes required where ultrasound can't be used.